The present invention relates to an improved tray for storing, shipping, and retaining instruments and other items necessary for conducting percutaneous transhepatic cholangiography (PTC) procedures in a sterile field or for conducting similar roentgenological visualizations by injection of a contrast medium, with or without suctioning of internal bodily fluids prior to injection. An aspect of the present invention relates to a two-piece slide-step tray assembly composed of an upper and a lower tray, the upper tray containing apparatus for preparing a sterile field, the lower tray containing the instruments necessary to complete a PTC procedure.
As known in the art, the PTC technique visualizes the biliary tree or biliary tract for radiographic examination or the like. It is a valuable tool in the diagnosis of, for example, biliary obstructions or jaundice, and can differentiate surgical from non-surgical conditions. The technique was carried out by Huard and Do-Xuan-Hop as early as 1937; see Bull. Soc. Med. Chir. Indochine 15:1090-1100 (1937). Today, the reliability of the PTC technique and its value to surgeons, radiologists, etc. should be considered established, see Seldinger, Acta Radiol. (Suppl) 253:1 (1966); Weichel, Acta Chir. Scand. (Suppl) 380:1 (1964); and Redeker, et al, JAMA 231:386 (1975).
Before conducting a PTC procedure, it is necessary that a sterile field be created. It is necessary to utilize separate materials for the different phases of the overall procedure, including the materials used to establish a sterile field and those materials used for the actual taking of a specimen. In the past, separate trays have been used sequentially, the first tray being employed to establish the steril field, the second tray containing the instruments necessary to perform the actual procedure. The use of an upper and a lower nested pair of trays for use in performing biopsy (as opposed to cholangiography) procedures is known in the art. See U.S. Pat. No. 3,987,895, issued Oct. 26, 1976. The upper tray of the nested pair contains the material necessary to establish a sterile zone while the lower tray contains the apparatus for performing the actual biopsy. A nested tray arrangement of this type allows the upper tray and materials to be discarded when the sterile field has been established and before the actual procedure is begun. The tolerance between the upper and the lower nested trays of the type described in U.S. Pat. No. 3,987,895 must be closely controlled since if the fit between the two trays is too tight the two trays may stick together while if the fit is too loose the top tray can fall out if the trays are inverted during shipment or if they are dropped during usage, causing the materials in both trays to be spilled.
A wide variety of tray structures are known in the art of surgery, diagnostic techniques, and other relatively unrelated fields such as food packaging or support. The biopsy procedure tray disclosed in the aforementioned U.S. Pat. No. 3,987,895 and the references cited in the file history thereof are believed to be illustrative of the state of the art; see, for example, U.S. Pat. No. 3,467,247 (Weiss), issued Sept. 16, 1969, U.S. Pat. No. 3,329,261 (Serany et al), issued July 4, 1967, and U.S. Pat. No. 3,567,067 (Weiss), issued Mar. 2, 1971.